Highly anisotropic nanocomposite Nd9Fe84.5Nb0.5B6 ribbons were obtained by rapid solidification at wheel speeds from 15 m/s to 20m/s. X-ray diffraction (XRD) shows that these ribbons are preferentially orientated with the c axis of Nd2Fe14B phase perpendicular to the surface of the ribbons. The anisotropy of Nd2Fe14B phase on the free surface is stronger than that on the contact surface and decreases with increase of wheel speed. The anisotropy of Nd2Fe14B phase seems to be caused by the preferential growth of the crystal nuclei favorable orientation with their c-axes along the temperature gradient during rapid solidification. The anisotropy of Nd2Fe14B phase decreases gradually after annealing above 600degreesC, which is mainly attributed to the precipitation of new alpha-Fe from Nd2Fe14B phase with super-saturated Fe. Decreasing the annealing temperature or reducing the annealing time is beneficial for preserving the anisotropy of Nd2Fe14B phase after annealing.